1. Field of the Invention
The present invention relates to the field of oral pharmaceutical compositions. More particularly, the present invention relates to an encapsulated calcium acetate caplet, and to a method for binding and inhibiting gastrointestinal absorption of phosphorous using an encapsulated calcium acetate caplet.
2. Background Information
A major focus of research and development efforts in the pharmaceutical industry is on the formulation of acceptable oral pharmaceutical compositions. More particularly, these efforts are concentrated on making oral pharmaceuticals that are palatable to the consumer. Chief among the concerns of pharmaceutical manufacturers in this area is the development of drugs that are as palatable as they are efficacious. The importance of these research efforts is greatest where the pharmaceuticals at issue are intended to ameliorate a patient's medical condition or alleviate their symptoms in cases of terminal illness. Chronic renal failure is one example of such an illness.
In cases of chronic renal failure, hyperphosphatemia, or excess phosphorus retention, plays a major role in the development of secondary hyperparathyroidism and osteodystrophy. Antacids or prescription medications are commonly used to manage or prevent hyperphosphatemia by binding dietary phosphorus and, thus, preventing its absorption into the gastrointestinal tract.
Phosphorous binders bind phosphorus in the form of a phosphorous ion within the stomach and intestines. This process is thought to result from a chemical reaction between dietary phosphorus and the cation present in the binder compound. The reaction causes the formation of insoluble and hence unabsorbable phosphate compounds. The cation in some phosphorous binders is aluminum or calcium. Despite their capacity for binding phosphorous, large quantities of antacids must be ingested over a long period of time for them to be effective. Therefore, dosage size and palatability are particularly important for patients with chronic renal disease.
Prescription medications typically effective in managing or preventing hyperphosphatemia include calcium acetate. Calcium acetate treatment is one of the most effective methods for management of chronic renal disease. When administered orally, calcium acetate is more effective than any other calcium-containing binder in binding phosphorus. Used alone or in combination with other materials, calcium acetate binds phosphorus in the gastrointestinal tract and reduces the percentage of consumed phosphorus (i.e., of a given “dose” of phosphorus) which is absorbed into the bloodstream. This compound is most effective in reducing phosphorous absorption when it is administered close in time to food consumption. Despite these benefits, calcium acetate treatments heretofore known in the art have not been without their drawbacks.
Calcium acetate is a naturally occurring solid. Like most solids found in nature, the bulk density of calcium acetate varies according to its source. Bulk density is the density, typically of a solid, as poured or passively filled into a measurement device. Bulk density can be determined by measuring the volume of a known mass (i.e., 125 g) of powder that has been passed into a graduated cylinder, followed by five “tamps” of the cylinder from a height of one (1) inch. Alternatively, it may be determined by measuring that volume of the known mass that has been passed through a volume measuring apparatus into a cup. While densities are normally expressed in grams per cm3, where measured in graduated cylinders, the bulk density of powder volumes are expressed in grams per mL, where cm3 and mL are equivalent volume units.
United States Pharmacopoeia (USP) is a widely recognized organization that sets some of the standards that pharmaceutical manufacturers must meet to sell their drugs and drug compounds in the United States. USP standards include procedures for the physical tests that must be performed on drugs and drug compounds to ensure compliance with the specific requirements set forth within these standards. USP #24 defines some of these standards for calcium acetate tablets. For example, physical test #711 on page 1941 of USP #24 sets forth the test to determine compliance with the dissolution standard set forth for calcium acetate tablets. USP #24 and #711 are incorporated herein by reference.
Pharmaceutical manufacturers in the art have heretofore used calcium acetate raw materials to form calcium acetate medications without regard to the density of the raw material fractions used. The result of this practice is that the manufacturers have been unable to produce a calcium acetate capsule or tablet of the usual dosage amount that is less than #00 in size, while passing test #711. An unfortunate consequence of the intrinsic characteristics of calcium acetate, and the practice of the pharmaceutical industry, is that patients needing this medication, such as end stage renal disease patients have heretofore found such medications difficult to swallow due to their bulk size. A second, equally undesirable characteristic of calcium acetate is that it has a chalky taste that is very unpleasant to the palate and is difficult to mask. Consequently, despite the obvious benefits of calcium acetate-based treatments, patients would typically fail to take the proper doses of their medicine, or turn to antacids as an alternative to these difficult-to-swallow unpalatable medications.
Calcium acetate compositions were heretofore no more desirable due to the dosing sizes, dosing requirements and the unpleasant taste associated with consumption of these medications. Accordingly, an encapsulated caplet that provides an effective dosage of medication for the treatment and management of terminal illnesses, without the risk of dosage side effects, is desired. An encapsulated caplet that also seals the taste of the medication and compresses the medication to ease or reduce the dosage volume necessary for effective illness treatment or management is desired, as well.